CN109476290B

CN109476290B - Vehicle with starting aid

Info

Publication number: CN109476290B
Application number: CN201780044646.1A
Authority: CN
Inventors: F·维尔纳
Original assignee: Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
Current assignee: Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
Priority date: 2016-07-19
Filing date: 2017-07-13
Publication date: 2021-05-25
Anticipated expiration: 2037-07-13
Also published as: WO2018015268A1; EP3487733A1; DE102016113249A1; CN109476290A; US10875509B2; US20190143949A1

Abstract

The invention relates to a vehicle (1) comprising: at least one driven shaft (6) and at least one non-driven shaft (10), on which at least one driven shaft (6) and on which at least one non-driven shaft (10) a wheel brake actuator (4, 8) is arranged in each case; an electrically controllable brake system comprises at least one electronic brake control device (2) which is designed to generate a brake application signal only for the wheel brake actuators (4) on the at least one driven axle (6) as a function of an input signal for at least partially applying the wheel brake actuators (4) only on the at least one driven axle (6). The invention is characterized in that a passive or active speed sensor (68) is provided on at least one wheel (12) of the at least one non-driven axle (10), said speed sensor having a measuring range covering a total speed range from zero to a maximum speed, said speed sensor (68) feeding a speed signal as an input signal into the electronic brake control device (2); signal generating means (56, 72, 80, 82) which generate a signal which is different from the wheel speed signal generated by the wheel speed sensor (68, 70) and which represents that the vehicle (1) is deliberately set in motion from a standstill and which is fed as an input signal into the electronic brake control device (2); the electronic brake control device (2) is designed to feed a brake application signal at least temporarily into the wheel brake actuators (4) of the at least one driven axle (6) if the rotational speed signal of the rotational speed sensor (68) corresponds to a rotational speed equal to zero and at the same time the signal of the signal generating means (56, 72, 80, 82) indicates that the vehicle (1) is deliberately set in motion from a standstill; if the rotational speed signal of the at least one rotational speed sensor (68) corresponds to a rotational speed which is not equal to zero, the electronic brake control device no longer feeds a brake application signal into the wheel brake actuators (4) of the at least one driven axle (6).

Description

Vehicle with starting aid

Technical Field

The present invention relates to a vehicle, comprising: at least one driven axle and at least one non-driven axle, wherein wheel brake actuators are provided on the at least one driven axle and the at least one non-driven axle, respectively; an electrically controllable brake system comprising at least one electronic brake control device configured to generate, in dependence on an input signal, a brake application signal only for wheel brake actuators on the at least one driven axle for at least partially applying brake application to wheel brake actuators only on the at least one driven axle.

Background

In principle, the transmission of force in a vehicle, which is responsible for moving the vehicle forward, depends on the driving slip between the tires and the roadway. Generally, the starting or acceleration process is carried out at low slip values, at which an increase in slip first also leads to an increase in the available force closure. However, the force closure is reduced again when the increase is continued, so that, in the case of a corresponding acceleration, the increased, excessive drive torque leads to a rapid increase in the rotational speed of the drive wheel or wheels.

The regulation of the drive slip, the so-called anti-slip control (ASR), prevents the drive wheels that slip as a result thereof and controls the drive slip to a permissible value. Such drive slip control is controlled by the prior art, for example, by "motor technology show treasure" (kraft fachrtechnisches Taschenbuch), publishers: robert Bosch GmbH, Dusseldorf, 21 st edition, page 555-. In the prior art, the drive slip is set in such a way that the drive torque is reduced when a limit value for the drive slip or a limit value for the time variation (time derivative) of the drive slip is reached. The reduction of the drive torque is achieved either by lowering the drive torque (in the internal combustion engine by adjusting the throttle or the ignition time) and/or by actuating one or more wheel brakes on the driven shaft/shafts. In particular, if a second, higher limit value for the drive slip is reached, the wheel brakes on the driven shaft/shafts can be automatically actuated in addition to the reduction of the drive torque (which takes place when the first limit value for the drive slip is exceeded).

As wheel speed sensors for driving anti-slip control (ASR), so-called passive sensors are generally used. Passive sensors are more cost-effective and less temperature sensitive than active sensors. An active sensor refers to a sensor that requires a supply voltage and that contains a temperature sensitive semiconductor. However, low speeds or rotational speeds and rotational directions of the wheels of the driven axle cannot be reliably identified with passive wheel speed sensors.

For example, in vehicles with ABS (anti-lock braking system, brake anti-skid control system) or EBS (electronic brake system), with and/or without ESP or EPB (electronic parking brake), with automatic transmissions or automated transmissions (which are parked or parked on slippery ice), the following can occur: the vehicle can no longer start on the basis of the "drive wheel trapping" effect, in which a water film forms under the tire as it heats up, but this water film freezes again, because the wheels of the driven axle will slip if the drive torque is too great. However, since such vehicles no longer have a clutch pedal, the driver can no longer influence the drive torque via the clutch. The possible drive slip control systems (ASR) often cannot be activated in this case, since the wheel speeds are mostly below the recognition speed threshold of the passive wheel speed sensor (approximately 3 to 10 km/h). The activation of the differential locking mechanism (differential lock wire) is also not further helpful if both wheels of the drive axle are on a smooth ground. ASR is activated if the driver gives more oil and increases the speed beyond the recognition speed threshold, but the drive torque cannot be reduced sufficiently, because the wheel speed must remain above the recognition speed threshold of the passive wheel speed sensor. Therefore, known ASR (drive anti-slip control through engine torque reduction and/or braking intervention on the driven axle/s) is only enabled at wheel speeds greater than about 3 to 10 km/h.

In order to implement the function of drive slip control in this case, it is therefore necessary to apply expensive active wheel speed sensors on the wheels of the driven axle instead of cost-effective passive wheel speed sensors.

Disclosure of Invention

In contrast, the object of the present invention is to further develop a vehicle of the type mentioned at the outset in such a way that, in a cost-effective manner, too high drive slip is prevented when starting from a standstill.

According to the invention, this object is achieved by the features of the invention.

The invention discloses:

the invention is based on a vehicle comprising:

at least one driven axle and at least one non-driven axle, wherein a wheel brake actuator is provided on each of the at least one driven axle and on the at least one non-driven axle;

an electrically controllable brake system comprising at least one electronic brake control device configured to generate, in dependence on an input signal, a brake application signal only for the wheel brake actuators on the at least one driven axle for at least partially applying only the wheel brake actuators on the at least one driven axle.

Such an electrically controllable brake system (which enables axle-only braking) is, for example, an EBS (electronically controlled brake system), in particular of a heavy goods vehicle, which in turn has, in particular, ABS (brake anti-skid control), ASR (anti-skid control) and ESP (electronic service stability program) functions. Each of the functions (ABS, ASR, ESP) is capable of individually braking a single axle and in this case in particular braking the driven axle. However, an electronically controlled parking or parking brake (EPB) can also individually brake individual axles and in this case in particular brake the driven axle, in particular the rear axle, to which the parking or parking brake is usually applied.

Thus, the present invention is characterized in that:

-providing a passive or active speed sensor on at least one wheel of at least one non-driven axle with a measurement range covering a total speed range from zero to a maximum speed, wherein the speed sensor feeds a speed signal as an input signal into the electronic brake control device;

-signal generating means which generate a signal which is different from the wheel speed signal generated by the wheel speed sensor and which represents that the vehicle is deliberately set in motion from a standstill and which is fed as an input signal into the electronic brake control device; wherein

The electronic brake control device is configured such that,

the electronic brake control device feeds a brake application signal at least temporarily into the wheel brake actuators of the at least one driven axle, provided that the rotational speed signal of the at least one rotational speed sensor (which sensor may be configured passively or actively) on the at least one non-driven axle corresponds to a rotational speed equal to zero and at the same time the signal of the signal generating means indicates that the vehicle is being deliberately set in from a standstill; and

if the rotational speed signal of the rotational speed sensor at least on the non-driven axle corresponds to a rotational speed which is not equal to zero, the electronic brake control device no longer feeds the brake application signal into the wheel brake actuators of the at least one driven axle.

In other words, instead of the wheel speed sensor, which is still a passive wheel speed sensor and is therefore cost-effective and robust, generating a signal representing or indicating the intentional driving of the vehicle from a standstill, a different signal generating means than the wheel speed sensor, for example an active speed sensor, which is often already present anyway, generates the above-mentioned signal, measures the rotational speed of the transmission output shaft of the transmission and feeds it as an input signal into the electronic brake control. If, for example, the electronic brake control device finds that the current rotational speed of the transmission output shaft of the transmission is greater than 0, this means that the vehicle is deliberately set in motion from a standstill.

Alternatively or additionally, the signal generating means may also generate a signal representing an intentional driving of the vehicle from a standstill, depending on an operation of the operating means, which may be operated by hand and/or foot, performed by the driver of the vehicle. Such an operating mechanism is then comprised by the signal generating mechanism.

In particular, the signal of the signal generating means, which signal represents an intentional actuation of the vehicle from a stationary state, may depend at least on an engaged or disengaged state of a clutch of the vehicle and/or on a selected transmission gear or a selected transmission mode and/or on an operation or non-operation of a brake pedal and/or on an operation or non-operation of an accelerator pedal and/or on an operation or non-operation of an operating means of a parking or parking brake. Therefore, if present, the clutch pedal, the accelerator pedal, the brake pedal, the shift lever or the select lever of the automatic transmission, and the operating mechanism (lever, rocker switch, key, etc.) of the parking or parking brake are the operating mechanisms of the signal generating mechanism. The signals can originate directly from sensors recording the operation of the actuator or can be derived indirectly from other variables.

For example, an accelerator pedal being operated, a selector lever of an automatically controlled transmission being in a drive position (driving or reverse), a brake pedal not being operated and (provided that there is a clutch operable by the driver) a clutch pedal not being operated means that the vehicle is deliberately set in motion from a standstill. Since the operation of the operating element is detected directly or indirectly by the sensor device which is already present and the corresponding signal is already present, for example, on the data bus of the vehicle, no additional sensor has to be provided to confirm that the vehicle is being deliberately set in motion from a standstill. Thus, according to a first aspect, the detection of an intentional driving of the vehicle from a standstill is automatically carried out by means of a sensor device which is already present or is still to be provided.

Alternatively or additionally, however, the signal generating means may also comprise additional operating means which can be operated individually by the driver and which are designed such that, independently of the operation of the clutch, transmission, brake pedal, accelerator pedal and parking or parking brake of the vehicle, they generate a signal which is different from the wheel speed signal generated by the wheel speed sensor and which represents the intentional driving of the vehicle from a standstill and which is fed as an input signal into the electronic brake control. Such an additional operating mechanism which can be operated by the driver alone can be, for example, a button or switch connected into the current circuit, which the driver can operate if he finds that the vehicle cannot be driven from a standstill on slippery ground without excessive drive slip. Subsequently, after the actuation of the actuating element, an electrical input signal for the electronic brake control is generated, which represents or indicates an intentional start of the vehicle from a standstill.

The additional operating element which can be operated by the driver alone is therefore understood to mean an operating element which differs from other operating elements which can be operated by the driver and with which the driver can influence the operating state of the vehicle, for example the accelerator pedal, the clutch pedal, the brake pedal or the operating element of the parking or parking brake.

If the above exemplarily described signal of the signal generating mechanism as an input signal for the electric brake control device indicates that the vehicle is being driven from a stationary state, whether forward or reverse, the electric brake control device is configured to: if the rotational speed signal of the at least one rotational speed sensor at VA corresponds to a rotational speed equal to zero and at the same time the signal of the signal generating means indicates that the vehicle is deliberately set in motion from a standstill, the electronic brake control device feeds a brake application signal at least temporarily into the wheel brake actuators of the at least one driven axle.

Thus, if at least one wheel speed sensor on the at least one non-driven axle informs the electronic brake control device of a speed of rotation substantially equal to zero, but on the other hand the signal of the signal generating means indicates that the vehicle is deliberately set in motion from a standstill, the wheels on the at least one driven axle must slip on the ground. The electronic brake control device then feeds the brake application signal at least temporarily into the wheel brake actuators of the at least one driven axle. The braking force or braking torque can be of any height, duration and can be any function of time. The person skilled in the art determines the braking force or the braking torque beforehand, for example on the basis of vehicle parameters. However, it is also conceivable to adapt the braking force or the braking torque as a function of the signal generating means. If, for example, it is found that the accelerator pedal is operated to a relatively large extent, but the wheel speed sensors on the at least one undriven axle still provide a zero value, a relatively large braking torque is still required compared to, for example, the case in which the accelerator pedal is operated to a relatively small extent. In the case of a time profile of the braking torque or braking force, i.e. the braking force or the braking torque as a function of time since the brake application signal was active, any arbitrary relationship is possible, in particular a ramp-shaped rise or a sudden fall of the braking force and an intermittent activation of the generation of the braking force, similar to that in ABS.

If the wheel then no longer slips or the drive slip no longer exceeds the permissible level in response to the braking force acting on the wheel of the at least one driven axle, this is determined in that the rotational speed signal of the at least one rotational speed sensor on the at least one non-driven axle corresponds to a rotational speed which is not equal to zero (forward or reverse), the electronic brake control no longer feeds the brake application signal into the wheel brake actuators of the at least one driven axle. Thus, the wheel successfully has a running state.

Thus, if, for the case when starting with slipping wheels, the drive wheels are braked by an electronic or electric brake system, for example an EBS with ABS and/or ASR and/or EPB (which in principle permits axle braking), the drive torque can be reduced in such a way that the drive wheels can again build up grip and can be started. The driver thus obtains a start assist which enables the driver to: the drive torque to be transmitted to the drive wheels is reduced compared to the setpoint drive torque. The starting aid also acts in particular below the detection threshold of the passive wheel speed sensor, since the brake application force is maintained for such a long time that the speed sensor on the at least one non-driven axle detects a stationary state of the vehicle or a driving state of the vehicle. The start assistance can be implemented using various already widely used electronically controlled brake systems, including for example ABS, ASR, ESP or EPB (electronically controlled parking brake). In particular, a vehicle equipped only with an electronically controlled parking or parking brake EPB can also realize such a start assist without additionally having an ABS, an ASR or an ESP on the service brake side.

The driver recognizes the necessity of a start assist by the fact that the driver, when engaged, supplies oil and the wheels on the driven axle slip and no traction situation exists. The driver can then operate, for example, a separate switch, lever or pushbutton as an operating mechanism, which then feeds the input signal into the electronic brake control device, which then generates a braking force on the wheel brakes of the at least one driven axle. In this case, for example, an ASR or ABS function implemented in an electronic brake control system can achieve a slow increase in the braking force, in the case of electropneumatic braking the brake pressure in the pneumatic wheel brake cylinders of the at least one driven axle being first increased to an application pressure (for example 0.3 bar) and then increased slowly in a ramp-like manner (for example 0.2 bar/sec) to a predetermined value. But a jump-up from zero to a parameterized value is also conceivable.

If the driver then again places the switch or button in the "off" position or the parameterized time limit runs out or a certain parameterized brake pressure is reached, the start assist is stopped and the brake force is reduced to zero again. The corresponding parameters have to be determined experimentally.

If an electrically controlled parking brake EPB equipped with spring brake cylinders is used for braking the drive wheels, the EPB reduces the pressure in the spring brake cylinders, for example, in a ramp manner or until a time limit or a specific pressure value in the spring brake cylinders is reached. These parameters must also be determined experimentally. The driver can here independently hold or raise or lower the accelerator pedal position, or freeze the accelerator pedal position and the engine torque remains automatically unchanged.

However, it is also possible to identify a situation in which the drive wheels slip in an otherwise stopped vehicle by using various sensor signals, as has already been described in detail above. This can be automatically detected if, for example, the rotational speed of the transmission output shaft, the engaged gear, the clutch signal and, for example, the rotational speed of the non-driven wheels on the front axle are known via a rotational speed sensor. The driven vehicle wheels slip slowly, which is detected by the rotational speed of the transmission output shaft, by the clutch signal when the clutch is engaged or closed, and the engaged gear is detected by the gear information. Furthermore, it is recognized from the signal of the electronically controlled parking brake that the parking brake is released, and from the accelerator pedal position and the brake pedal position that the driver is supplying oil, the brake is released and the driver is about to start the vehicle. However, since the vehicle does not move because the driven wheels slip, the wheel speed signal of the speed sensor, for example on the front axle, does not indicate the speed. Then, as described above, a braking force is automatically applied to the driven wheel and the effective drive motor torque is thereby reduced until the driven wheel again gains grip. If the wheel speed on the front axle is not equal to zero as detected by the speed sensor, the braking force on the driven wheel is again removed. If the vehicle stops again and the driven wheel slips again, the process starts over.

The electronic brake control device, in which the driver-triggered or automatically triggered start assistance is implemented, can be designed as a separate control device or integrated in a further control device, which in addition also performs a function different from the braking function.

Advantageous refinements and improvements of the invention are possible by means of the measures cited in the description and the drawing.

Particularly preferably, the signal of the signal generating means is related to the rotational speed of a transmission output shaft of a vehicle transmission. The signal generating means may comprise at least one active speed sensor which measures the speed of the transmission output shaft of the transmission and feeds it as an input signal into the electronic brake control device. Since such active speed sensors are often already present on the transmission output shaft of the transmission, additional sensors for implementing the start-up assistance can be dispensed with.

Alternatively or additionally, the signal generating means may generate a signal which is different from the wheel speed signal generated by the wheel speed sensor and which represents an intentional driving of the vehicle from a standstill, as a function of a manual and/or foot-operated actuation of the actuating means performed by the driver of the vehicle. The signal of the signal-generating means can be dependent at least on the engaged or disengaged state of the clutch of the vehicle; and/or depending on the selected transmission gear or selected transmission mode; and/or dependent on operation or non-operation of the brake pedal; and/or dependent on operation or non-operation of the accelerator pedal; and/or dependent on operation or non-operation of the parking or parking brake. These signals are often already present on the data bus of the vehicle, for example.

The above-described embodiments thus relate to the automatic recognition of a start-up situation. Alternatively or additionally, the driver can activate the start assist himself.

Alternatively or additionally, the signal generating means may therefore comprise additional operating means which are independently operable by the driver and which are designed such that, independently of the operation of the clutch, transmission, brake pedal, accelerator pedal and parking or parking brake of the vehicle, they generate a signal which is different from the wheel speed signal generated by the wheel speed sensor and which represents the intentional driving of the vehicle from a standstill and which is fed as an input signal into the electronic brake control. The start assist is activated by the driver actuating the operating element. The operating element can be designed such that the start aid is always activated as long as the operating element is operated. Alternatively, however, each actuation of the actuator can also cause a switch from "active" to "inactive" or vice versa, or an "active" or "on" position of the actuator and an "inactive" or "off" position of the actuator are already provided.

Preferably, a brake application signal provided to the electrically controllable brake actuators of the at least one driven axle for at least partially pressing the brake actuators on the at least one driven axle is configured such that it generates an at least temporarily acting brake torque at the wheels of the at least one driven axle. The braking torque acting at least temporarily on the wheels of the at least one driven axle can here rise in a ramped or linear manner from zero to a predetermined value, have a predetermined value in a jumping manner or be effective over one or more predetermined time intervals. Thus, any time variation of the braking force or the braking torque is conceivable. Furthermore, the braking force or the braking torque can be automatically adapted as a function of vehicle parameters, in particular on the basis of a characteristic map.

The electrically controllable brake system is preferably a service brake system, wherein the wheel brake actuator is a wheel brake actuator of a service brake; alternatively, the electrically controllable brake system is a parking brake system, wherein the wheel brake actuator is a wheel brake actuator of a parking brake.

In particular, the functions of the brake slip control (ABS) and/or the drive slip control (ASR) and/or the Electronic Stability Program (ESP) and/or the Electronic Parking Brake (EPB) are preferably implemented in the electronic brake control, since these functions can in principle implement independent, axle-specific braking of the driven axle and therefore do not have to be fundamentally changed in the programming of the electronic brake control.

Preferably, the electrically controllable brake system is an electronically controlled electro-pneumatic brake system (EBS), and the electronic brake control device is an electronic brake control device of the electronically controlled electro-pneumatic brake system (EBS). This likewise has the advantage that functions such as ABS, ASR and ESP, with which the driven axle can be braked independently and independently of the non-driven axle, have already been integrated in such electronically regulated electro-pneumatic brake systems (EBS).

Advantageous further developments of the invention emerge from the claims, the description and the drawings. The advantages of the features and combinations of features mentioned in the introduction to the description are merely exemplary and can be brought into effect alternatively or cumulatively without forcing the achievement of these advantages by embodiments according to the invention.

Further features can be derived from the figures (in particular the geometry shown and the relative dimensions of the various components to one another and their relative arrangement and functional connection). Features of different embodiments of the invention or combinations of features of different claims may also differ from the chosen relation of reference of the claims and the teaching thereof is given here. This also relates to features shown in separate drawings or referred to in the description thereof. These features may also be combined with the features of different claims. Likewise, features recited in the claims for further embodiments of the invention may be omitted.

Components and assemblies that are identical or functionally identical are each denoted by the same reference numerals in the different embodiments.

Drawings

The invention is explained in more detail below with reference to the figures according to embodiments.

The sole figure shows a schematic representation of parts of a vehicle with an electro-pneumatic brake system according to a preferred embodiment of the invention.

Detailed Description

The preferred embodiment of the vehicle 1 shown in the figures, in particular a heavy goods vehicle, has, for example, an electrically operated electronically controlled brake system EBS, in which the braking force is electronically controlled. The electronically controlled brake system EBS preferably has ABS, ASR and ESP functions and can therefore brake only the wheel brakes 4 on the driven rear axle 6 individually via its brake control 2, while the wheel brakes 8 on the non-driven axle 10 are not stressed. However, in normal braking operation, the brake control device 2 can also apply the

wheel brakes

4, 8 on the two

axles

6, 10 in parallel. The

wheel brakes

4, 8 in this case comprise, for example, pneumatic brake cylinders which act on brake actuators like disk brakes.

In the vehicle 1, therefore, there is an undriven axle 10 with two front wheels 12, a driven rear axle 6 with preferably two driven rear wheels 14, an engine 16, a transmission 18, a clutch 20 arranged between the engine 16 and the transmission 18, and a transmission output shaft 22, which transmission output shaft 22 drives the wheels 14 of the rear axle 6, for example, via a cardan shaft and a rear axle differential.

In addition,

pneumatic lines

24, 26, 28, 30, 32, 34 of the electro-pneumatic electronically controlled brake system EBS for supplying the control pressure or the brake pressure, as well as data lines 36, 38, 40, 42, 44, 46, 48, 50, which are depicted by dashed lines and through which information and control commands are transmitted, are also provided in the vehicle 1.

The pneumatic lines 28 and 34 and the data line 50 are connected to a brake value generator 54 with a brake pedal 56 for the service brakes of the electro-pneumatic electronically controlled brake system EBS, wherein the brake value generator 54 has two pneumatic channels here, namely a pneumatic channel 58 for the control pressure of the front axle 10 and a pneumatic channel 60 for the control pressure of the rear axle 6, and furthermore an electrical channel 62. The two

pneumatic channels

58 and 60 each supply the associated shaft with compressed air using their own compressed air reservoir, not shown here.

Thus, when the brake pedal 56 of the brake value generator 54 is operated, on the one hand an electric brake request signal is fed via the data line 50 into the electric brake control device 2. The pressure regulating modules 64 of the wheel brakes 8 for the front axle 10 and the pressure regulating modules 66 of the wheel brakes 4 for the rear axle 6 are electrically actuated by the electronic brake control via the data lines 38, 42. In parallel with this, on the other hand, when the brake pedal 56 is actuated, the corresponding control pressure reaches the pressure regulating modules 64, 66 via the pneumatic lines 28 and 34, but is only available if the control via the electrical channel 62, the data lines 50, 38 and 42 and the electronic brake control device 2 fails. The pressure regulating modules 64, 66 each contain, in a known manner, an inlet-outlet solenoid valve combination (which controls an integrated relay valve), a backup solenoid valve for maintaining the pneumatic control pressure in the pressure lines 28 and 34, and a pressure sensor for each channel and are each connected to an associated compressed air reservoir for the front axle 10 or for the rear axle 6. In addition, the pressure regulating modules 64 and 66 are preferably each designed as a two-channel pressure regulating module, wherein each channel regulates the brake pressure in the

wheel brakes

4, 8 on the vehicle side to a respective desired target brake pressure.

The EBS therefore preferably has an electrically operated front axle brake circuit and an electrically operated rear axle brake circuit.

The pressure regulating modules 64, 66 then feed corresponding brake pressures into the wheel brakes 8 of the front axle via the

pneumatic lines

24, 26 and into the wheel brakes 4 of the rear axle 6 via the

pneumatic lines

30, 32 as a function of the electric brake request signal in the electric line 62 or as a function of the pneumatic control pressure in the

pneumatic lines

58, 60 of the brake value generator 54.

The electronically controlled brake system EBS is preferably equipped with a brake slip control system ABS. For this purpose and for further functions, such as ASR and ESP, the front wheels 12 and the rear wheels 14 are each assigned a

wheel speed sensor

68, 70. Thus, during braking, the actual wheel revolutions are transmitted via the data lines 36, 48 or 40, 44 to the electronic brake control device 2 and the actual brake slip is calculated here for each wheel. If the actual brake slip exceeds the predetermined target brake slip, the brake control device 2 preferably adjusts the brake pressure via the pressure control modules 64, 66 in a channel-like manner such that the target brake slip at the

respective wheel

12, 14 is no longer exceeded.

The wheel speed sensors 70 on the rear axle are preferably designed as passive wheel speed sensors. The passive wheel speed sensor does not recognize the direction of rotation of the wheels 14 on the rear axle 6. And also at very low speeds the speed cannot be identified. However, this is not necessary for braking anti-skid control systems (ABS) from medium and high speeds. In this respect, the passive wheel speed sensor is relatively cost-effective.

Passive or active wheel speed sensors 68 may likewise be provided on the wheels 12 of the non-driven axle 10. These wheel speed sensors 68 feed wheel speed signals via the data lines 36, 48 into the brake control device 2. If active wheel speed sensors 68 are used, these active wheel speed sensors, in contrast to passive speed sensors, also allow a reliable detection of very low rotational speeds and rotational directions of the wheels 12 of the non-driven axle 10, which can advantageously influence the detection of a start. In particular, they can determine the difference between zero and very small rotational speeds of the wheels 12 on the front axle 10, which leads to an improved start recognition. However, this principle is also applicable to passive sensors.

Furthermore, an active speed sensor 72 may be provided on the transmission output shaft 22 of the transmission 18 and connected to the transmission control device 74 via the data line 46. The transmission output shaft 22 is coupled in rotation with the rear wheels 14 in a manner not shown here, so that the rotation of the rear wheels 14 and the direction of rotation thereof can be detected by the active speed sensor 72 and a signal fed as an input signal into the transmission control device 74.

The data lines 36 to 44 and 48 to 50 CAN be connected directly to the brake control device 2 as shown or CAN be connected to the brake control device 2 via a data bus, for example a CAN bus.

The

rotational speed sensors

68 and 72 can be designed such that they scan the teeth of the gears, not shown here, on the transmission output shaft 22 or on the drive shaft of the front axle 10. Alternatively, an additional polar ring with teeth can also be provided on the transmission output shaft 22 or on the drive shaft, which teeth are subsequently scanned by the

rotational speed sensors

68 and 72.

The transmission 18 is preferably an automated transmission with a transmission control 74. The clutch 20 is electrically actuated by a transmission control device 74, for example. Both the transmission control device 74 and the brake control device 2 are connected to a CAN bus 76. The data of the active speed sensor 72, which measures the speed of the transmission output shaft 22, are thus distributed here via the transmission control device 74 and the CAN bus 76 and are thus also supplied to the brake control device 2. Furthermore, a signal is also provided via the data bus 76 to the brake control device 2, which signal provides information about the position of a selector lever (N, D, R or P range), not shown here, of the automatic transmission.

According to an embodiment not shown here, the transmission 18 can also be a manual transmission which is not automated. In this case, the brake control device 2 receives a signal which provides information about the position of a selector lever of the transmission (N, gear step or reverse) via a corresponding sensor and by means of a data line.

An engine control device 78 that controls the engine 16 is also connected to the data bus 76. An electric accelerator pedal 80 having at least one sensor for measuring the accelerator pedal position and/or the operating speed of the accelerator pedal 80 feeds a drive request signal corresponding to the operating level of the accelerator pedal 80 into the engine control device 78. Since the engine control 78 is likewise connected to the data bus 76, a signal is also provided via the data bus 76 to the brake control device 2 which provides information about whether the accelerator pedal 80 is operated or not operated and in particular also about the level of operation of the accelerator pedal.

The electric clutch 20 is controlled by an electric signal of the transmission control device 74, which is also fed via a data bus 76 into the brake control device 2, which is then provided with information about the state (engaged or disengaged) of the clutch 20. Furthermore, an electrical path 62 through the brake value generator 54 also has a sensor on the accelerator pedal 56, which feeds the operating state (inoperative, normal operating or operating level) of the accelerator pedal 56 via the data line 50 into the brake control device 2. In particular, the inoperative parking or parking brake (which the vehicle preferably also has here) can also represent a signal for the intentional activation of the vehicle from a standstill. The actuation or non-actuation of the actuating element of the parking or parking brake can be determined by a corresponding electrical signal, in particular when the parking or parking brake is electrically controlled.

An intentional start of the vehicle 1 from a standstill can then be signaled to the brake control device 2 by a signal of at least one of the

sensors

22, 62 and 80 present here. If it is determined, for example, by the electronic brake control device 2: the current rotational speed of the transmission output shaft 22 of the transmission 18, measured by the active speed sensor 72, is greater than a rotational speed which corresponds to idling of the engine 16 or an idling rotational speed band containing tolerances, which then means that the vehicle 1 is deliberately set in motion from a standstill.

Furthermore, for example, the actuated accelerator pedal 80, the selector lever in the driving position (D or R) of the transmission 18, which is preferably automated here, the non-actuated brake pedal 56 and the clutch 20 in the engaged state mean that the vehicle 1 is deliberately set in motion from a standstill.

It is therefore preferred here to detect an intentional start of the vehicle 1 from a standstill automatically as a function of at least one of the

sensors

62, 72 and 80. The sensor signal of the at least one

sensor

62, 72 and 80 is subsequently compared in the brake control device 2 with a reference value, so that an intentional actuation can be detected.

Alternatively or additionally, there may also be an additional operating element 82 which is separately operable by the driver and which is likewise connected to the brake control device 2 via a data line 84.

The additional driver-independently actuable operating element 82 is designed and designed such that it can generate a signal, which represents the intentional actuation of the vehicle 1 from a standstill and which is fed as an input signal into the electronic brake control device 2, independently of further driver-actuable operating elements, such as the brake pedal 56 or the accelerator pedal 80. The additional driver-independently actuable actuating element 82 may comprise, for example, a lever-actuated selector switch connected into the circuit, wherein the driver can pivot the lever into a position "on" and into a position "off". Then, in the position "on", a signal representing that the vehicle 1 is deliberately set in motion from a stationary state is fed into the brake control device 2, and in the position "off", the generation of this signal is inhibited.

If the driver finds it impossible to start intentionally from a standstill on slippery ground without excessive drive slip, i.e. if the wheels 14 of the driven rear axle 6 slip at start-up, he can, for example, put the lever of the operating element 82 from the position "off" into the position "on".

If the wheels 14 of the driven rear axle 6 slip on slippery ground and excessive drive slip is to be avoided, a starting aid for the vehicle 1 can be achieved with the components and assemblies of the above-described preferred embodiment.

Then, the electronic brake control device 2 is configured to: if the speed signal of the speed sensor 68 on the front axle 10 corresponds to zero speed and at the same time a signal from at least one sensor of the group of active speed sensors 72 on the transmission output shaft 22 and/or on the electrical channel 62 of the brake value generator 54 and/or a sensor of the accelerator pedal 80 indicates that the vehicle 1 is deliberately set in motion from a standstill, the electronic brake control device feeds a brake application signal at least temporarily into the pressure regulating module 66 of the driven rear axle 6. Subsequently, the intentional driving of the vehicle 1 from a stationary state is automatically detected. However, the signals of the wheel speed sensors 70 on the wheels 14 of the rear axle 6 are preferably not taken into account here, since their speed resolution is too low at low speeds.

Alternatively or additionally, the signal generated when the driver adjusts the additional operating element 82 into the position "on" and fed into the brake control device 2 may represent an intentional actuation of the vehicle 1 from a standstill.

Thus, if the speed sensor 68 on the front axle 10 detects a speed equal to zero, this means that a vehicle stationary state is still present, even if the signals of the

further sensors

22, 62 and 80 already indicate that the vehicle 1 is deliberately set in motion from the stationary state, for example by a higher rotational speed than the idling speed by means of the already operated accelerator pedal 80 and/or by means of the not operated brake pedal 56 and/or by means of the rotating transmission output shaft 22. In this case, therefore, the wheels 14 of the rear axle 6 are considered to slip on the ground and too high a drive slip is present.

Consequently, the brake control device 2 then generates a brake application signal only for the pressure regulating module 66 of the driven rear axle 6 in order to generate a braking torque at the rear axle 6 that acts on a drive torque that is too high, which results in slipping of the wheels 14.

Additionally, the driver also recognizes the necessity of start assistance in that the vehicle 1 is not moving and the wheels 14 on the rear axle 6 slip despite the selector lever of the transmission 18 being in position "D", the brake pedal 56 not being operated and the accelerator pedal 80 being operated. The driver can then optionally operate the operating mechanism 82 to the position "on", whereby an input signal is fed into the electronic brake control device 2, which electronic brake control device 2 then generates a braking force on the wheel brakes 4 of the rear axle 6.

That is, the starting assistance consists in generating a braking force/torque on the driven rear axle 6 in order to counteract a slip of the wheels 14. In general, the start-up assistance can be activated automatically on the one hand by means of the above-described

sensor devices

22, 56, 68 and 80, alternatively by the driver by means of the operating element 82, or both of these alternatives can complement one another.

The ASR, ABS and ESP functions implemented in the electronic brake control device 2 can in this case effect a slow increase in the braking force, in the case of an electropneumatic braking of the brake pressure of the wheel brakes 4, for example of the pneumatic wheel brake cylinders of the driven rear axle 6, first to the application pressure (for example 0.3 bar) and then slowly ramp-up (for example 0.2 bar/sec) to a predetermined value. However, a sudden increase from zero to a parameterized value of the brake pressure can also be taken into account.

The invention is not limited to an electropneumatic brake system, but rather can be implemented in all electrically controllable brake systems, for example purely electric brake systems, or also in electro-hydraulic brake systems.

Alternatively or additionally to the braking intervention, the drive torque of the engine 16 may also be reduced if the necessity of a start assist is automatically detected and subsequently activated and/or triggered by the operating element 82. The brake control device 2 then (also) controls the engine control device 78 in order to reduce the drive torque when slipping of the wheels 14 of the driven rear axle 6 is detected automatically or by the driver.

If the rotational speed signal of the rotational speed sensor 68 on the front axle 10 then signals a number of revolutions to the brake control device 2 after a certain time, which means that traction is present and the wheels are moving in the desired direction, the brake control device 2 then no longer feeds a brake application signal into the pressure regulating module 66 of the driven rear axle 6, so that the vehicle brakes 4 are released there. Alternatively or additionally, the driver, after recognizing the presence of traction on the rear axle 6, can also switch the operating element 82 from the position "on" to the position "off", so that the brake control device 2 likewise switches off the start-up assistance.

List of reference numerals:

1 vehicle

2 brake control device

4 rear axle wheel brake

6 rear axle

8 front axle wheel brake

10 front axle

12 front wheel

14 rear wheel

16 engine

18 speed variator

20 Clutch

22 output shaft of speed changer

24 pneumatic pipeline

26 pneumatic pipeline

28 pneumatic line

30 pneumatic line

32 pneumatic line

34 pneumatic pipeline

36 data line

40 data line

42 data line

44 data line

46 data line

48 data line

50 data line

54 braking value generator

56 brake pedal

58 front axle pneumatic channel

60 rear axle pneumatic channel

62 electric channel

64 front axle pressure regulating module

66 rear axle pressure regulating module

68 front axle wheel speed sensor

70 rear axle wheel speed sensor

72 speed sensor

74 Transmission control device

76 CAN data bus

78 engine control device

80 Accelerator pedal

82 operating mechanism

84 data lines.

Claims

1. A vehicle (1) comprising:

a) at least one driven shaft (6) and at least one non-driven shaft (10), wherein a wheel brake actuator (4, 8) is arranged on each of the at least one driven shaft (6) and on the at least one non-driven shaft (10);

b) an electrically controllable brake system comprising at least one electronic brake control device (2) configured to generate, in dependence on an input signal, a brake application signal only for wheel brake actuators (4) on the at least one driven axle (6) for at least partially applying the wheel brake actuators (4) only on the at least one driven axle (6); it is characterized in that the preparation method is characterized in that,

c) -a passive or active speed sensor (68) is provided on at least one wheel (12) of the at least one non-driven axle (10), with a measuring range covering a total speed range from zero to a maximum speed, wherein the speed sensor (68) feeds a speed signal as an input signal into the electronic brake control device (2);

d) signal generating means (56, 72, 80, 82) which generate a signal which is different from the wheel speed signal generated by the wheel speed sensor (68, 70) and which represents that the vehicle (1) is deliberately set in motion from a standstill and which is fed as an input signal into the electronic brake control device (2); wherein

e) The electronic brake control device (2) is configured such that,

e1) if the rotational speed signal of the rotational speed sensor (68) corresponds to a rotational speed equal to zero and at the same time the signal of the signal generating means (56, 72, 80, 82) indicates that the vehicle (1) is deliberately set in motion from a standstill, the electronic brake control device feeds a brake application signal at least temporarily into the wheel brake actuators (4) of the at least one driven axle (6); and is

e2) If the rotational speed signal of the at least one rotational speed sensor (68) corresponds to a rotational speed which is not equal to zero, the electronic brake control device no longer feeds a brake application signal into the wheel brake actuators (4) of the at least one driven axle (6).

2. The vehicle according to claim 1, characterized in that the signal of the signal generating means (72) is related to the rotational speed of a transmission output shaft (22) of a transmission (18) of the vehicle (1).

3. Vehicle according to claim 2, characterized in that the signal generating means (72) comprise at least one active speed sensor which measures the speed of rotation of the transmission output shaft (22) of the transmission (18) and feeds it as an input signal into the electronic brake control device (2).

4. Vehicle according to claim 1, characterized in that the signal generating means (82) generate a signal which differs from the wheel speed signal generated by the wheel speed sensor (68, 70) and which represents an intentional start of the vehicle (1) from a standstill, as a function of an operation of the hand-and/or foot-operable operating means (82) performed by the driver of the vehicle.

5. Vehicle according to claim 4, characterized in that the signal of the signal generating means (56, 80) is related to at least the engaged or disengaged state of the clutch (20) of the vehicle (1); and/or is related to a selected transmission gear or a selected transmission mode of the transmission (18); and/or in relation to the operation or non-operation of the brake pedal (56); and/or in relation to the operation or non-operation of an accelerator pedal (80); and/or in connection with the operation or non-operation of the operating mechanism of the parking or parking brake.

6. Vehicle according to claim 4 or 5, characterized in that the signal generating means (82) comprise an additional operating means (82) which can be operated individually by the driver and are configured such that they generate a signal which differs from the wheel speed signal generated by the wheel speed sensors (68, 70) and which represents an intentional activation of the vehicle (1) from a standstill and which is fed as an input signal into the electronic brake control device (2), independently of the operation of the clutch (20), the transmission (18), the brake pedal (56), the accelerator pedal (80) and the parking or parking brake of the vehicle (1).

7. Vehicle according to one of claims 1 to 5, characterized in that a brake application signal provided to the electrically controllable brake actuators (4) of the at least one driven axle (6) for at least partially pressing the brake actuators (4) on the at least one driven axle (6) is configured such that it generates an at least temporarily acting brake torque on the wheels (14) of the at least one driven axle (6).

8. Vehicle according to claim 7, characterized in that the braking torque acting at least temporarily on the wheels (14) of the at least one driven axle (6) ramps from zero to a predetermined value, jumps to a predetermined value or is effective over one or more predetermined time intervals.

9. Vehicle according to one of claims 1 to 5, characterized in that the electrically controllable brake system is a service brake system, wherein the wheel brake actuators (4, 8) are wheel brake actuators of a service brake; or the electrically controllable brake system is a parking brake system, wherein the wheel brake actuator is a wheel brake actuator of a parking brake.

10. Vehicle according to one of claims 1 to 5, characterized in that the function of brake anti-skid control (ABS) and/or Electronic Parking Brake (EPB) and/or anti-skid control of the drive (ASR) and/or Electronic Stability Program (ESP) is implemented in the electronic brake control device (2).

11. Vehicle according to one of claims 1 to 5, characterized in that the electrically controllable brake system is an electronically controlled electro-pneumatic brake system (EBS).